1. Field of the Invention
The present invention relates to a homogeneous acrylonitrile olefinically unsaturated multipolymer and a process to make the same. This multipolymer has molecularly uniform monomer sequences throughout the multipolymer, has a high nitrile polymer content and is melt processable. More specifically, the invention relates to a monomer starved process for producing an acrylonitrile olefinically unsaturated multipolymer in which the polymerization rate exceeds or equals the addition rate of the multimonomers of acrylonitrile monomers and olefinically unsaturated monomer(s).
2. Description of the Prior Art
Acrylic polymers are high nitrile polymers which are desirable in the production of fibrous textiles, films, molded objects, packaging applications and the like. High nitrile polymers have excellent physical, thermal and mechanical properties such as barrier properties, chemical resistance, rigidity, heat resistance, UV resistance, moisture retention and bacteria resistance.
However, acrylic polymers and multipolymers having long repeating sequences of acrylonitrile monomer units are known to degrade when heated and processed by commercial methods. The long sequences of nitrile units make the acrylic high nitrile polymers non-processable without the use of solvent.
Thermoplastic nitrile barrier polymer resins are known in the art and have been described in U.S. Pat. Nos. 3,426,102 and 3,586,737. These nitrile polymers are known to have desirable barrier properties and chemical resistance. However, these thermoplastic nitrile polymers while melt processable are difficult to process.
U.S. Pat. No. 5,106,925 discloses a thermoplastic nitrile polymer. However, the process to produce the nitrile polymer is based on tracking the polymer conversion and adding the reactants in the same mount as they are removed and converted to polymer. This process must make proper adjustments in rates and quantities throughout the polymerization process.
It is desirable to produce thermoplastic high nitrile multipolymers by a process in which the nitrile monomer units are uniformly sequenced throughout the chain. It is advantageous to produce a homogeneous acrylonitrile olefinically unsaturated multipolymer with improved thermoplastic properties and a high nitrile content which multipolymers are melt processable in the absence of a solvent. It is an object of the invention to make a nitrile polymer chain with uniformly sequenced and short sequences of the nitrile monomer in a process that has a fixed monomer feed ratio.